Infrastructure for Common Lisp Ports: Overhaul

• Decouple ASDF initialization from devel/cl-asdf by creating a dedicated port: devel/freebsd-cl-asdf-init.
• Convert devel/cl-asdf/bsd.cl-asdf.mk to USES=cl.
• Add devel/cl-asdf-sbcl
• Update ASDF configuration:
  • Prefer newer ASDF versions, but only if the fasl is available.
  • Replace license text with an SPDX license identifier.
  • Simplify and clarify documentation.
  • Remove the assumption that ${PREFIX} is /usr/local.
  • Use uiop:getenv instead of a custom getenv function.
  • Remove asdf:output-files customization to resolve output translation issues.
  • Improve output translations:
    • Prevent writing fasls to ${PREFIX}/lib/common-lisp/ when the corresponding fasl port is not installed.
    • Fall back to ASDF's default caching mechanism of writing fasl to a cache under ${HOME} when users install a Common Lisp port without its fasl port.
  • Improve interoperability with Common Lisp code from sources outside of ports, such as Quicklisp.
  • Add support for Clozure Common Lisp (CCL)

Approved by: olgeni (implicit)
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D47983